High isolation E-plane array MIMO antenna

Abstract

This invention discloses a high-isolation E-plane MIMO antenna, comprising a first and a second dielectric substrate, with the first dielectric substrate stacked on the second dielectric substrate. The upper and lower surfaces of the first dielectric substrate are respectively provided with a first and a second copper-clad layer. A metasurface radiating structure, composed of two identical rectangular patch elements arranged side-by-side, is provided on the first copper-clad layer. Decoupling probes are provided in the two middle rows of rectangular patches of the metasurface radiating structure, connecting the metasurface radiating structure to the second copper-clad layer. Coupling slots and decoupling slots are respectively provided on the second copper-clad layer. A third copper-clad layer is provided on the lower surface of the second dielectric substrate, and first and second feed networks are provided on the third copper-clad layer. This invention can achieve broadband high-isolation decoupling between two zero-pitch metasurface antennas. Its element pattern is stable, the maximum radiation direction does not deflect, the structure is simple, the profile is low, and the integration is high, showing great application potential.

Description

Technical Field

[0001] This invention relates to the technical field of communication antennas, and in particular to a high-isolation E-plane array MIMO antenna. Background Technology

[0002] Metasurface antennas are widely used in wireless communication systems due to their wide bandwidth, low profile, and ease of fabrication. To meet the high-speed transmission requirements of next-generation wireless communication systems, Multiple-Input Multiple-Output (MIMO) technology has become a key technology. The communication capacity of a MIMO system can increase linearly with the number of antennas. However, coupling between antennas leads to a sharp decline in system efficiency and performance. In previous designs, the decoupling bandwidth of MIMO antennas was typically narrow, and expanding the decoupling bandwidth inevitably resulted in a decrease in isolation. Decoupling techniques using band-stop structures, due to their resonant structure, exhibit a sharp decrease in decoupling effectiveness when deviating from the resonant frequency. Furthermore, band-stop structures require space between two antenna elements, limiting further miniaturization of MIMO antenna modules. Existing mode cancellation techniques can utilize the superposition of two modes to cancel the field at the feed position of one antenna element, thus achieving zero-pitch or even common-radiator decoupling. However, they typically struggle to simultaneously achieve wideband decoupling and high-isolation decoupling. By utilizing the superposition of characteristic mode fields, due to the correlation of characteristic mode fields at adjacent frequencies, it is possible to ensure that they maintain a certain cancellation effect near the designed decoupling frequency point, thus possessing the potential for broadband high-isolation decoupling.

[0003] An investigation and understanding of existing technologies was conducted, specifically as follows:

[0004] Q. Lai et al. proposed a method for making metasurface antennas TM in 2025. 01 Mode and Inverting TM 02 The metasurface antenna with E-plane arrangement constructed by mode superposition has a slightly narrower decoupling bandwidth than conventional metasurface antennas. Furthermore, due to the fact that its antenna structure is not completely equal, the decoupling structure needs to be redesigned when it is extended into a linear array.

[0005] In 2025, B. Qian et al. proposed a decoupling method for E-plane arranged patch antennas with decoupling patch structure loading. By loading a parasitic patch layer on top of the E-plane arranged patch antenna as a decoupling patch layer, the in-band isolation can be improved from 17 dB to 44 dB. However, due to the characteristics of the antenna structure, its operating bandwidth is relatively narrow.

[0006] In summary, previous research on decoupling metasurface MIMO antennas has focused on antennas arranged along the magnetic field polarization direction (H-plane) to improve isolation and throughput in mobile communication systems. However, research on decoupling MIMO antennas arranged along the electric field polarization direction (E-plane) remains limited. Combining E-plane and H-plane antenna decoupling techniques could facilitate the construction of large-scale MIMO arrays.

[0007] Therefore, it is of great significance to design a simple and effective E-plane MIMO antenna that can simultaneously achieve broadband and high isolation characteristics. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings and deficiencies of existing technologies and provide a simple and reliable high-isolation E-plane MIMO antenna. Decoupling nulls are introduced in the high-frequency and low-frequency regions through decoupling slots on the copper-clad layer and decoupling probes connecting the metasurface radiating structure and the copper-clad layer, respectively. Simultaneously, the initial design dimensions are selected by analyzing the cancellation effect of the decoupling slots and decoupling probes on the operating mode field. This antenna can operate stably in the 3.3GHz-4.2GHz frequency range, with a reflection coefficient of less than -10dB in this range; and a zenith gain greater than 8.15dBi in the passband.

[0009] To achieve the above objectives, the technical solution provided by this invention is as follows: a high-isolation E-plane MIMO antenna, comprising a first dielectric substrate and a second dielectric substrate, wherein the first dielectric substrate is stacked on the second dielectric substrate; a first copper-clad layer and a second copper-clad layer are respectively provided on the upper and lower surfaces of the first dielectric substrate; a metasurface radiating structure is provided on the first copper-clad layer, wherein the metasurface radiating structure is formed by two identical rectangular patch units arranged side by side, wherein the rectangular patch unit is an n x n rectangular patch array, where n ≥ 3; the middle two columns of rectangular patches of the metasurface radiating structure are provided with decoupling probes, wherein the two columns of rectangular patches... The substrate consists of two rectangular patch units, each with a column of rectangular patches. The decoupling probe connects the metasurface radiation structure to the second copper layer, introducing a decoupling zero in the low-frequency range. The second copper layer has coupling gaps and decoupling gaps. The coupling gaps are located directly below the metasurface radiation structure to couple energy to the structure and radiate it into space. The decoupling gaps are located directly below the vertical axis of symmetry of the metasurface radiation structure, introducing a decoupling zero in the high-frequency range. The lower surface of the second dielectric substrate has a third copper layer. The third copper layer has a first feed network and a second feed network.

[0010] Preferably, the first power supply network includes a first power supply port, a first impedance input feed line, a first impedance transformation line, and a first impedance output feed line connected in sequence. The first power supply network splits the input signal into two paths and couples the energy to the metasurface radiation structure of the first copper layer through the coupling gap on the second copper layer to generate radiation.

[0011] Preferably, the second power supply network includes a second power supply port, a second impedance input feed line, a second impedance transformation line, and a second impedance output feed line connected in sequence. The second power supply network splits the input signal into two paths and couples the energy to the metasurface radiation structure of the first copper layer through the coupling gap on the second copper layer to generate radiation.

[0012] Preferably, the first impedance input feed line and the second impedance input feed line are 50-ohm characteristic impedance input feed lines, and the first impedance transformation line is a 70.7-ohm characteristic impedance transformation line.

[0013] Preferably, the first impedance output feed line and the second impedance output feed line are 50-ohm characteristic impedance output feed lines, and the second impedance transformation line is a 70.7-ohm characteristic impedance transformation line.

[0014] Preferably, the thicknesses of the first dielectric substrate and the second dielectric substrate are 0.76 mm and 3 mm, respectively, the length is 80 mm, the width is 100 mm, the dielectric constant is 2.55, and the loss tangent is 0.0019.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0016] This invention utilizes decoupling slots and decoupling probes to introduce two decoupling nulls in the high-frequency and low-frequency ranges respectively, achieving broadband, high-isolation decoupling between two metasurface antennas under zero-pitch conditions. It features stable element patterns, no deflection of the maximum radiation direction, simple structure, low profile, and high integration, showing great application potential. Furthermore, the initial design dimensions are selected by analyzing the cancellation effect of the decoupling slot and probe dimensions and their loading positions on the operating mode field. This invention can operate stably in the 3.3GHz-4.2GHz frequency range, with a reflection coefficient less than -10dB in this range and a zenith gain greater than 8.15dBi in the passband. Attached Figure Description

[0017] Figure 1 This is an exploded view of the antenna of the present invention.

[0018] Figure 2 This is a cross-sectional view of the antenna of the present invention.

[0019] Figure 3This is a schematic diagram of the structure of the first copper cladding layer.

[0020] Figure 4 This is a schematic diagram of the structure of the second copper cladding layer.

[0021] Figure 5 This is a schematic diagram of the third copper cladding layer.

[0022] Figure 6 This is a schematic diagram of the current distribution of the two characteristic modes used in the antenna of this invention.

[0023] Figure 7 The variation of the superimposed electric field intensity of the antenna mode in the high-frequency region with the length of the decoupling gap is shown.

[0024] Figure 8 The mode superposition electric field intensity of the antenna of the present invention varies in the low-frequency region with the loading position of the decoupling probe.

[0025] Figure 9 The figure shows the simulation results of the S-parameters of the antenna of this invention.

[0026] Figure 10 The figure shows the simulation results of the gain and envelope correlation coefficient (ECC) curves of the antenna of the present invention.

[0027] Figure 11 This is a simulated radiation pattern of the center frequency of the antenna of this invention. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0029] See Figures 1 to 5As shown, this embodiment discloses a high-isolation E-plane MIMO antenna, including a first dielectric substrate 2 and a second dielectric substrate 4, wherein the first dielectric substrate 2 is stacked on the second dielectric substrate 4; the upper and lower surfaces of the first dielectric substrate 2 are respectively provided with a first copper-clad layer 1 and a second copper-clad layer 3; a metasurface radiating structure 11 is provided on the first copper-clad layer 1, wherein the metasurface radiating structure 11 is formed by two identical rectangular patch units arranged side by side, wherein the rectangular patch unit is an n-row n-column rectangular patch array, where n≥3, and in this embodiment specifically n=4; the middle two columns of rectangular patches of the metasurface radiating structure 11 are provided with decoupling probes 12, wherein the two columns of rectangular patches are two rectangular Each of the patch units has a row of rectangular patches; the decoupling probe 12 connects the metasurface radiation structure 11 to the second copper cladding layer 3, introducing a decoupling zero in the low-frequency part; the second copper cladding layer 3 is provided with coupling gap 31 and decoupling gap 32 respectively; the coupling gap 31 is located directly below the metasurface radiation structure 11, and is used to couple energy to the metasurface radiation structure 11, and then radiate it into space; the decoupling gap 32 is located directly below the vertical axis of symmetry of the metasurface radiation structure 11, and introduces a decoupling zero in the high-frequency part; the lower surface of the second dielectric substrate 4 is provided with a third copper cladding layer 5; the third copper cladding layer 5 is provided with a first feed network 51 and a second feed network 52.

[0030] Preferably, the first power supply network 51 includes a first power supply port 511, a first impedance input feed line 512, a first impedance transformation line 513, and a first impedance output feed line 514 connected in sequence. The first power supply network 51 splits the input signal into two paths and couples the energy to the metasurface radiation structure 11 of the first copper layer 1 through the coupling gap 31 on the second copper layer 3 to generate radiation.

[0031] Preferably, the second power supply network 52 includes a second power supply port 521, a second impedance input feed line 522, a second impedance transformation line 523, and a second impedance output feed line 524 connected in sequence. The second power supply network 52 splits the input signal into two paths and couples the energy to the metasurface radiation structure 11 of the first copper layer 1 through the coupling gap 31 on the second copper layer 3 to generate radiation.

[0032] Preferably, the first impedance input feed line 512 and the second impedance input feed line 522 are 50-ohm characteristic impedance input feed lines, and the first impedance transformation line 513 is a 70.7-ohm characteristic impedance transformation line.

[0033] Preferably, the first impedance output feed line 514 and the second impedance output feed line 524 are 50-ohm characteristic impedance output feed lines, and the second impedance transformation line 523 is a 70.7-ohm characteristic impedance transformation line.

[0034] Preferably, the thicknesses of the first dielectric substrate 2 and the second dielectric substrate 4 are 0.76 mm and 3 mm, respectively, the length is 80 mm, the width is 100 mm, the dielectric constant is 2.55, and the loss tangent is 0.0019.

[0035] See Figure 6 As shown in the figure, the side-fire operation mode of the high isolation E-plane array MIMO antenna described in this embodiment is displayed. It can be seen from the figure that simultaneously stimulating the two modes can achieve the superposition of current on the side of the excited antenna and the mutual cancellation of the mode current on the side of the unexcited antenna element.

[0036] See Figure 7 As shown in the figure, the superposition electric field intensity of the mode in the high isolation E-plane MIMO antenna of this embodiment varies with the length of the decoupling gap in the high frequency band. It can be seen from the figure that the design size of the decoupling gap can be obtained according to the control effect of the decoupling gap length on the superposition electric field.

[0037] See Figure 8 As shown in the figure, the superposition electric field intensity of the mode of the high isolation E-plane MIMO antenna described above in this embodiment changes with the loading position of the decoupling probe in the low frequency band. It can be seen from the figure that the loading position of the decoupling probe can be obtained according to the control effect of the loading position of the decoupling probe on the superposition electric field.

[0038] See Figure 9 As shown in the figure, the S-parameter simulation results of the high isolation E-plane array MIMO antenna of this embodiment are displayed. It can be seen from the figure that the frequency range in which the antenna reflection coefficient of the present invention is less than -10 dB is 3.3 GHz-4.2 GHz, the port isolation is greater than 30 dB, and the relative bandwidth is more than 24%.

[0039] See Figure 10 As shown in the figure, the gain curve and envelope correlation coefficient (ECC) simulation results of the high isolation E-plane array MIMO antenna of this embodiment are displayed. It can be seen from the figure that the antenna gain of the present invention is greater than 8.15 dBi in the side-fire mode in the frequency range of 3.3 GHz-4.2 GHz, and the ECC is less than 0.012, which has high gain and low envelope correlation coefficient.

[0040] See Figure 11 As shown, the simulation results of the radiation pattern of the high isolation E-plane MIMO antenna of this embodiment are displayed. It can be seen from the figure that the antenna of the present invention can produce a good side-firing radiation pattern when fed by port one (i.e., the first feed port) and port two (i.e., the second feed port). The maximum radiation direction of the radiation pattern is not deflected, and the cross-polarization level of the two main planes is better than -40 dB, which has a low cross-polarization level.

[0041] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A high-isolation E-plane array MIMO antenna, characterized in that, The system includes a first dielectric substrate (2) and a second dielectric substrate (4), with the first dielectric substrate (2) stacked on the second dielectric substrate (4). The upper and lower surfaces of the first dielectric substrate (2) are respectively provided with a first copper cladding layer (1) and a second copper cladding layer (3). A metasurface radiation structure (11) is provided on the first copper cladding layer (1), the metasurface radiation structure (11) being composed of two identical rectangular patch units arranged side-by-side. The rectangular patch unit is an n x n column rectangular patch array, where n ≥ 3. Decoupling probes (12) are provided in the two middle columns of rectangular patches of the metasurface radiation structure (11), where the two columns of rectangular patches are one column of rectangular patches from each of the two rectangular patch units. The decoupling probes (12) The metasurface radiation structure (11) is connected to the second copper clad layer (3) to introduce a decoupling zero in the low-frequency part; the second copper clad layer (3) is provided with a coupling gap (31) and a decoupling gap (32); the coupling gap (31) is located directly below the metasurface radiation structure (11) to couple energy to the metasurface radiation structure (11) and then radiate it into space; the decoupling gap (32) is located directly below the vertical axis of symmetry of the metasurface radiation structure (11) to introduce a decoupling zero in the high-frequency part; the lower surface of the second dielectric substrate (4) is provided with a third copper clad layer (5); the third copper clad layer (5) is provided with a first feed network (51) and a second feed network (52).

2. The high-isolation E-plane MIMO antenna according to claim 1, characterized in that, The first power supply network (51) includes a first power supply port (511), a first impedance input feed line (512), a first impedance transformation line (513), and a first impedance output feed line (514) connected in sequence. The first power supply network (51) splits the input signal into two paths and couples the energy to the metasurface radiation structure (11) of the first copper layer (1) through the coupling gap (31) on the second copper layer (3) to generate radiation.

3. A high-isolation E-plane MIMO antenna according to claim 2, characterized in that, The second power supply network (52) includes a second power supply port (521), a second impedance input feed line (522), a second impedance transformation line (523), and a second impedance output feed line (524) connected in sequence. The second power supply network (52) splits the input signal into two paths and couples the energy to the metasurface radiation structure (11) of the first copper layer (1) through the coupling gap (31) on the second copper layer (3) to generate radiation.

4. A high-isolation E-plane MIMO antenna according to claim 3, characterized in that, The first impedance input feed line (512) and the second impedance input feed line (522) are 50-ohm characteristic impedance input feed lines, and the first impedance transformation line (513) is a 70.7-ohm characteristic impedance transformation line.

5. A high-isolation E-plane MIMO antenna according to claim 4, characterized in that, The first impedance output feed line (514) and the second impedance output feed line (524) are 50-ohm characteristic impedance output feed lines, and the second impedance transformation line (523) is a 70.7-ohm characteristic impedance transformation line.

6. A high-isolation E-plane MIMO antenna according to claim 5, characterized in that, The first dielectric substrate (2) and the second dielectric substrate (4) have thicknesses of 0.76 mm and 3 mm, respectively, lengths of 80 mm, widths of 100 mm, dielectric constants of 2.55, and loss tangents of 0.0019.

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